Tag Archives: Seedling starter pot

We geocoded maternal residential addresses listed on the birth certificates using an automated approach

Since most pesticide applications are spatially explicit and the usage may vary over years, these studies face challenges of lacking high spatial and temporal resolution for exposure assessment, on top of the known ecological fallacy. On the other hand, individual level GIS-based studies that assessed exposure to agricultural pesticides in proximity to residences, have shown inconsistent findings. A recent Spanish study explored the possible association between childhood renal tumors and residential proximity to environmental pollution sources by calculating the percentage of total crop surface within a 1-km buffer around each individual’s last known residence and discovered that children living in the proximity of agricultural crops have higher risk of developing renal cancer . However, US studies of individual measures of agricultural pesticides in proximity to residences, mostly suggested no association with childhood cancers, or at best modest associations for certain types of cancers and chemicals or chemical groups. A Texas study measured crop field density within a 1-km buffer of residence at birth for both cases and controls born in 1990-1998 to study the risk for childhood cancers by sub-types and found no evidence of elevated risk associated with residential proximity to cropland for most childhood cancers, except for modestly positive associations with non-Hodgkin lymphoma , Burkitt lymphoma , and other gliomas. A California population-based case-control study of early childhood cancer used mothers’ residential addresses at the time of birth to evaluate risks associated with residential proximity to agricultural applications of pesticides during pregnancy and also found no associations with most specific chemicals and chemicals groups,plastic planters except for modestly elevated ORs for leukemia associated with probable and possible carcinogen use and with nearby agricultural applications of organochlorines and organophosphates.

They suggested that the few elevated risk associations for specific chemicals including metam sodium and dicofol in this study are likely due to chance from multiple comparisons . Another Northern California study assessed residential proximity within a half-mile of pesticide applications by linking address histories with reports of agricultural pesticide use and examined the association of the first year of life or early childhood pesticide exposures and childhood acute lymphoblastic leukemia and suggested elevated ALL risk was associated with lifetime moderate exposure to certain physicochemical groups of pesticides, including organophosphates ,cholorinated phenols , and triazines , and with pesticides classified as insecticides or fumigants.These results vary by chemicals or chemical groups examined, and methods of exposure assessment, and therefore produced inconsistent results. In addition, many of the above studies found no or week associations between all cancer types grouped together and proximity to crop fields, agricultural activities, specific agents, or groups of chemicals. It may problematic because the etiologies of most childhood cancer sub-types remain largely unknown and may not share the same causal pathway mediated by pesticides. As mentioned before, these studies of ambient pesticide exposures in pregnancy or early childhood, often assign exposures based upon the child’s or mother’s residence. While large scale record-linkage studies can avoid selection and recall biases that often impact smaller studies with active subject recruitment, previous record-based studies often relied solely on maternal residential address at birth, which is readily available on many birth certificates and/or residential address at diagnosis, as was done in some childhood cancer studies . Previous evidence suggested that exposure to pesticides before or during pregnancy may harm the developing fetus. Nevertheless, increased risks were seen for postnatal period as well. For instance, a study of childhood leukemia tried to distinguish between pre-pregnancy, pregnancy and postnatal exposures as critical windows for household pesticide exposure, and insecticide exposures early in life appear to be significant, though the effect is not as strong as prenatal exposures .

After birth, children may also be more susceptible to the harmful effects of pesticides than adults, as they have more actively dividing cells , providing the rationale to studies of childhood cancers not only focus on prenatal but also early life exposures. The reliance on one address for assessment of exposures in the first year of life or early childhood implicitly makes the assumption that a child’s residence remained the same throughout the entire period of interest, or if they moved, that the exposure levels remained the same. Even if some studies assessed exposures as the children’s residential proximity to agricultural fields or pesticide applications at the time of birth, these exposure indicators at birth are assumed to reflect exposures in prenatal and/or postnatal period, which are believed to be critical windows of exposures for childhood cancers. Consequently, the “one-address” approach may lead to exposure misclassification for those who moved in early childhood especially for exposures with high spatial heterogeneity. In a 2003-2007 California statewide representative survey, only 14% of all women moved in the 2-7 months post-partum , but with increasing age of the child, the frequency of residential moves also increased. For more than 50% of childhood cancer cases under age 5 diagnosed in California between 1988 and 2005, address at birth differed from the address at cancer diagnosis , which raises concerns about using residence at birth to assess exposures in early childhood. Exposure misclassification due to moving is a ubiquitous problem encountered by nearly all record-based studies that lack a complete residential history for each child. Previous studies suggested that residential mobility may be associated with certain risk factors for childhood cancers such as maternal age, marital status, parity, family income, and other socioeconomic status metrics , resulting in non-differential or even differential misclassification of exposures. Currently, in the US, the privilege of having an accurate complete residential history still only belongs to interview-based environmental epidemiological studies, which are often quite small with hundreds of subjects because of high time and monetary costs of such interviews and likely under powered.

Small case-control studies typically asked for individuals’ lifetime residential histories , including the beginning and end dates for each address. Large cohort studies follow participants over for a long time and often update their addresses periodically from follow-up questionnaires, so they may not know the exact moving dates. Sometimes these studies additionally collect information from the US Postal Service change-of-address forms or major credit reporting agencies, but the date associated with each address does not necessarily capture an accurate “move-in” date, but rather reflects the first known date . While it is not feasible to acquire complete residential histories from interviews for all subjects in large record-based studies as a gold standard to compare against the recorded birth or diagnosis address, databases containing public records of individuals collected by commercial companies have become available in recent years, allowing us to trace individuals without a self reported residential history. For example, LexisNexis Public Records, Inc. , a commercial credit reporting company,plastic nursery plant pot provides all known addresses for a set of individuals upon request. If the commercial residential history data has relatively high accuracy, their low cost and broad coverage would provide valuable information to all studies requiring residential history data . The basic service provided by LexisNexis returns the latest three known addresses while the enhanced service, with a higher cost, returns all known addresses from at least 1995. This database was maintained primarily for the purpose of contacting study participants but not for scientific research use, and therefore may not be as accurate as residential history obtained from interviews or self-administrated questionnaires. Several earlier studies have attempted to compare reconstructed residential history based on LexisNexis records with interview-based residential history for enrolled subjects and validate its use for research purposes. A Michigan case-control study of bladder cancer first compared lifetime residential histories collected through written surveys and 3 residential addresses available in LexisNexis and reported 71.5% match rate . Their bladder cancer cases were less than 80 years of age upon diagnosis, and controls were selected from similar age groups. Both cases and controls had lived in 1 of the 11 counties in Michigan for more than 5 years before recruitment in 2008-2009. Another US-wide study selected a random sample of 1000 subjects originally enrolled in the National Institutes of Health-American Association of Retired Persons Diet and Health Study, with AARP members aged 50–69 years and living in one of six US states or two metropolitan areas at the time of enrollment. Authors found 72% and 87% detailed address match rates with the basic and enhanced services provided by LexisNexis, respectively . The most recent LexisNexis validation study looked into participants in California Teachers Study, a prospective cohort study initiated in 1995-1996 and originally designed to study breast cancer. These women aged between 22 to 104 years at enrollment , and lived throughout California. The study pointed out that though the overall match rate between the two sources of addresses was good , it was diminished among black women and younger women . In summary, such residential information from LexisNexis, if of high quality, could potentially augment existing address information and help us reconstruct residential histories for subjects in large record-linkage studies and provide more accurate exposure estimates.

However, researchers should be aware that residential mobility of young children or their mothers may be different from that of mid-aged or older population, who were the majority in all three validation studies discussed above and believed to have a more stable residence. In addition, differences in distributions of race/ethnicity, socioeconomic status, and geographic regions may influence residential mobility in various study populations as well.During the 1st decade of the 21st century, the estimated rates of preterm birthand low birth weightpeaked at 11%-13% and 7%-8% in the US, respectively . Though survival of infants born preterm and/or low birthweight has improved in the last decades due to advancements in prenatal and neonatal care, they are more susceptible to adverse health outcomes such as neurodevelopmental impairment, respiratory and gastrointestinal complications , obesity, diabetes mellitus, hypertension, and kidney disease ; they also result in substantially higher infant and childhood mortality rates . California is the largest agricultural state in the United States, with more than 150 million pesticide active ingredients applied every year . Previous experimental studies show that various pesticides, including organophosphates and pyrethroids, can influence prenatal development related to adverse birth outcomes .Proposed mechanisms include disturbance of placental functions , endocrine disruption , immune regulation and inflammatory mechanisms . Pesticides have been found in indoor residential dust in residences near agricultural fields, and may persist for years . However, epidemiologic studies yielded inconsistent results, specifically while ecological and cross-sectional studies reported positive associations for PTB and LBW and pesticide use in agriculture , results from studies assessing self-reported or occupational use of pesticides were inconsistent . A systematic review of 25 studies examining agriculture-related exposures from residential proximity to pesticide applications suggested weak or no effects on preterm birth and low birth weight, possibly due to the methodological difficulties of exposure assessment . More recent residential proximity studies using simple or aggregate-level exposure assessments provided some evidence for pesticide influencing birth outcomes . Two recent Geographic Information System -based studies restricted to the San Joaquin Valley of California reported conflicting results – one found pesticide exposures to increase preterm birth and low birthweight by 5-9% in those highly exposed to chemicals with acute toxicity as based on the US EPA Signal Word , while the other assessed 543 individual chemicals and 69 physicochemical groupings found negative associations for spontaneous preterm birth . Nevertheless, various small pesticide biomarker-based studies with measured organochlorines, organophosphates, or pyrethroids and their metabolic breakdown products in maternal blood or urine or umbilical cord blood suggested positive associations with preterm birth or with lower birthweight but results varied by chemicals and outcomes assessed . Here, we assessed GIS-derived exposures during pregnancy to selected agricultural pesticides applied near maternal residences and risks of preterm birth and term low birthweight, considering trimester-specific exposure windows in a large sample of births in agricultural regions of California.Birth addresses with a low geocode quality due to missing or non-geocodeable fields on the birth certificates accounted for ~12% of all addresses geocoded. We then calculated measures of residential ambient pesticide exposures using a GIS-based Residential Ambient Pesticide Estimation System, as previously described . In brief, since 1974 agricultural pesticide applications for commercial use are recorded in Pesticide Use Reports mandated by the CA Department of Pesticide Regulation .